The present invention relates to a catalytic combustion apparatus or the like using liquid fuel, and more particularly to an evaporation method of liquid fuel, especially an art of reducing power consumption required for evaporation.
As methods for evaporating liquid fuel, a method for dropping liquid fuel in an evaporation unit for evaporation, a method for evaporating liquid fuel via an evaporation element located in an evaporation unit for injection thereafter, or the like has been used in oil burning appliances for home use and well known.
In any of the methods, heat recovery to the evaporation unit is performed by heat conduction from an evaporation heat recovery ring located at a flame port of formed flame or from an evaporation heat recovery receiving unit disposed with part thereof extending into the flame.
In the above described conventional evaporation apparatus, atmosphere temperature of the formed flame and the vicinity thereof is 1100xc2x0 C. to 1300xc2x0 C. and high, so that heat recovery to the evaporation unit performed by the heat conduction from the evaporation heat recovery ring located at the flame port or from the evaporation heat recovery receiving unit disposed with part thereof extending into the flame sometimes allows self heat combustion.
However, in a catalytic combustion apparatus, a catalytic combustion unit has temperature limited to 900xc2x0 C. or less that is a limit of heat resistance, and is a heat recovery source of lower temperature, so that it is difficult to achieve self heat combustion in a configuration of an evaporation unit like the conventional one, and a heater for continuously heating the evaporation unit is separately required.
However, there is a problem that the heater for heating the evaporation unit requires high power consumption. There is also a disadvantage that uniform heating and evaporation of the liquid fuel is difficult, causing part of the fuel to recondense (to become tar) and deposit in the evaporation unit.
The present invention has the object to provide a fuel evaporation apparatus that solves the problems of the conventional catalytic combustion apparatus and the fuel evaporation apparatus, and that allows evaporation heat to be sufficiently obtained without separate use of a heater for continuously feeding the evaporation heat.
To achieve the above object, one aspect of the present invention is a fuel evaporation apparatus, comprising:
fuel feeding means of feeding liquid fuel;
air feeding means of feeding air;
a carburetor for evaporating said fuel;
an auxiliary catalytic combustion unit provided in contact with or close to said carburetor;
a gas mixture space that is provided between said carburetor and said auxiliary catalytic combustion unit, which holds said evaporated fuel and said air, wherein
said auxiliary catalytic combustion unit has a plurality of compartments provided from upstream to downstream of a flow of said gas mixture, and
that said compartments carry catalysts on all or part thereof and are provided with gas mixture vents through which said gas mixture passes.
Another aspect of the present invention is the fuel evaporation apparatus according to the 1st invention, wherein said air feeding means feeds the air into said carburetor.
Still another aspect of the present invention is the fuel evaporation apparatus, wherein said air feeding means feeds the air into said gas mixture space.
Yet still another aspect of the present invention is the fuel evaporation apparatus, wherein it comprises an air feeding port opening into said gas mixture, and
that said air passes through said carburetor and is fed from said air feeding port into said gas mixture space.
Still yet another aspect of the present invention is the fuel evaporation apparatus, wherein at least one of said compartments has an air diversion port disposed downstream of said air feeding port, and
that part of the air fed from said air feeding port passes through said air diversion port to be diverted.
A further aspect of the present invention is the fuel evaporation apparatus, wherein said catalysts are carried on all of said compartments, and
that said air diversion ports of said compartments have smaller diameters at more downstream positions along the flow of said gas mixture.
A still further aspect of the present invention is the fuel evaporation apparatus according to the 1st invention, wherein said compartments come into contact with said carburetor at their ends,
that among said compartments, the compartment positioned upstream of the flow of said gas mixture is covered with the compartment positioned downstream of the flow of said gas mixture at a predetermined distance, and
that said gas mixture passes around said compartment positioned upstream of the flow of said gas mixture.
A yet further aspect of the present invention is the fuel evaporation apparatus, wherein a gas mixture vent of said compartment positioned upstream of the flow of said gas mixture and a gas mixture vent of said compartment positioned downstream of the flow of said gas mixture are provided in such a manner that central axes of said gas mixture vents do not coincide with each other.
A still yet further aspect of the present invention is the catalytic combustion apparatus, wherein the most downstream compartment, or at least a surface thereof facing said catalytic combustion unit is formed from high emissivity base material.
An additional aspect of the present invention is the fuel evaporation apparatus, wherein the most downstream heating element compartment, or at least a surface thereof facing said catalytic combustion unit is coated with base material having high emissivity.
A still additional aspect of the present invention is the fuel evaporation apparatus, wherein said catalyst is carried on parts other than a surface facing said carburetor of the most upstream compartment and a surface facing said catalytic combustion unit of the most downstream compartment.
A yet additional aspect of the present invention is the fuel evaporation apparatus, wherein said compartments are disposed at a distance not more than a quenching distance.
A still yet additional aspect of the present invention is a catalytic combustion apparatus comprising:
the fuel evaporation apparatus,
a catalytic combustion unit provided downstream of said auxiliary catalytic combustion unit; and
a second gas mixture space that is provided between said auxiliary catalytic combustion unit and said catalytic combustion unit and holds said evaporated fuel and said air.
A supplementary aspect of the present invention is the catalytic combustion unit, wherein a straightening vane disposed to oppose said air diversion port is provided in said second gas mixture space.
The above described present invention provides, as an example, a catalytic combustion apparatus including: a fuel feeding passage for feeding liquid fuel; an air feeding passage for feeding air; a carburetor provided with a heater; a catalyst heating element disposed in contact with or close to the above described carburetor; a gas mixture space provided between the above described carburetor and the above described catalytic heating element; and a catalytic combustion unit having a plurality of communication passages located downstream of the above described catalyst heating element, characterized in that the above described catalyst heating element carries an oxidization catalytic component and includes a plurality of heating element compartments having gas mixture vents, that the above described plurality of heating element compartments are disposed in a flow direction of the gas mixture, and that the gas mixture having passed through an upstream heating element compartment thereby successively passes through a downstream heating element compartment.
A catalytic combustion apparatus according to another embodiment of the present invention is characterized in that an air injection port at a tip of an air feeding passage penetrates a carburetor such that air does not come into contact with the carburetor, that air diversion ports are provided, at downstream positions of the air injection port, in the heating element compartments included in a catalyst heating element, and that air is diverted in such a manner that part of the air passes through the air diversion ports and does not come into contact with the catalyst heating element.
A catalytic combustion apparatus according to a further embodiment of the present invention is characterized in that the most upstream heating element compartment carries an oxidation catalytic component, that the most downstream heating element compartment is formed from high emissivity base material, or that at least surface thereof facing a catalytic combustion unit is coated with high emissivity material, and that the heating element compartments are disposed in contact with a carburetor.
A catalytic combustion apparatus according to a further embodiment of the present invention is characterized in that gas mixture vents are disposed in such a manner that gas mixture having passed through a gas mixture vent of an upstream heating element compartment collides with a downstream heating element compartment.